Unless the oil is overfilled or the engine operated on a steep angle, I would suspect blowby. If it is blowby, worn rings or stuck rings would be the usual culprits, other symptoms would be oil consumption, oil on plug, or frequently fouled plug. I personally have not had a valve issue cause oil to be pushed out the pcv, but I can't say that I have seen it all. Good luck.
oil in aircleaner
:trink39: hi all, im looking for sum help on a 12 hp brigs motor i just got. 1st of all the motor runs great, no smoking or rough runing. that being said the problem im having is oil is coming outa of the tube that comes from what looks kinda like a pvc valve to the air cleaner. i use to have a 8hp that did the same thing, a friend told me i needed a valve job. is this the case or is there another simple fix for this? i dont know if its a pvc valve or not for sure but you can take it off and inside you can see the valve stems. thanks for any help
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I would not rebuild until I checked a few other things, if the plug is clean, blowby may not be the issue. Might be simple as a defective PCV, it should allow air out, but the reed valve should not allow it back into the engine.
As for the compression, B&S has refused for many years to publish compression data in their service manuals, unless they started recently. The standard they recomended was to rotate the flywheel backwards against the compression stroke, if it bounced back it has enough to run. Valve stem clearence being a far more common loss of compression and power than rings/cylinder wear in these motors. B&S does not consider an engine to be using excessive oil unless in burns more than 4 oz/hour.
If the engine is running well and the oil in the breather is not enough to cause the plug to foul or engine to miss, I would ignore that in favor of watching for more serious indications like oil consumtion, or quickly fouled plugs.
As for the compression, B&S has refused for many years to publish compression data in their service manuals, unless they started recently. The standard they recomended was to rotate the flywheel backwards against the compression stroke, if it bounced back it has enough to run. Valve stem clearence being a far more common loss of compression and power than rings/cylinder wear in these motors. B&S does not consider an engine to be using excessive oil unless in burns more than 4 oz/hour.
If the engine is running well and the oil in the breather is not enough to cause the plug to foul or engine to miss, I would ignore that in favor of watching for more serious indications like oil consumtion, or quickly fouled plugs.
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